The proposed Barbados Incidence Study of Eye Diseases II (BISED II) aims to collect 9-year incidence and progression data on open-angle glaucoma (OAG) and age-related cataract in the predominantly black population of Barbados, West Indies, as well as to obtain natural history data on age- related macular changes and diabetic changes. OAG and cataract are the two major causes of blindness in populations of African origin, accounting for about half of visual loss. Despite their high prevalence and public health importance, data on blacks are limited and no clear explanation for the increased risk exists. Early macular changes were frequent in the BES. Although diabetic retinopathy was less common, about one-fifth of the population has diabetes, thus raising questions about risk factors for DR in a black population. BISED II provides a unique opportunity to obtain the first long term incidence and progression data on a large population- based cohort, as such longitudinal data are not available for black populations. BISED II will provide new information concerning natural history and underlying factors for these chronic, life-long eye diseases, to assist in understanding etiology, identifying groups at high risk, and developing strategies to control visual loss. A shorter follow-up is insufficient to provide this information. To achieve these aims, BISED II will re-examine the surviving cohort of the Barbados Eye Study (BES). The BES was conducted from 1988 to 1992 to measure prevalence and risk factors for OAG, cataract, age-related macular degeneration and diabetic retinopathy, while providing baseline data for further incidence measurements. The BES was followed by the Barbados Incidence Study of Eye Diseases (BISED; 1992-1997), which is determining 4-year incidence and progression for these conditions. High participation rates of 84% and 85% were achieved by BES and BISED, respectively, among the eligible cohort. The positive response of the cohort and the past experience gained in conducting BES and BISED enhance the feasibility of successful follow-up. Given the cohort size, follow-up rates of incidence and progression can be estimated with high precision. Given the high prevalence and incidence, a wide range of relative risks can be detected. In summary, the BES cohort is a unique resource to study the major causes of blindness and provides an opportunity to learn, for the first time, about their long-term patterns of occurrence in a black population. This information may assist to address major racial differences in prevalence and has important public health implications.